Apparatus for producing thermionic effects



May 12, 1925. 1,537,528

C. D. EHRET APPARATUS FOR PRODUCING THERMIONIC EFFECTS Filed April 29,1919 PLA T VOL 7A GE Patented May 12, 1925.

UNITED STATES GORNIilLIIJ'S D. EHRET, OF PHILADELPHIA, PENNSYLVANIA.

APPARATUS FOR PRODUCING THERMIONIC EFFECTS.

Application filed April 29, 1919. Serial No. 293,485.

To all whom it may concern:

Be it known that I, \CORNELIUS D. EHRET, acitizen of the UnitedStates,'residing in the city and county of Philadelphia, State ofPennsylvania, have invented a new and useful Apparatus for ProducingThermionic Effects, of which the following is a specification.

My-invention relates to apparatus for producing thermionic effects,particularly in circuits comprising a space, preferably with in avacuum, traversed by electrons for effecting current variation orcontrol, for the purposes of amplification, rectification, production ofoscillations, or other effects. I

My invention resides in apparatus of the character referred tocharacterized by the fact that upon a plate or anode circuit isimpressed fluctuating or alternating current, with or without thepresence of a source of current, as a battery, in the anode or platecircuit, With suitable control, as by a grid element whose potentialdepends upon the fluctuating electro-motive-force in the anode or platecircuit or upon a fluctuating electro- Inotive-force superimposed uponanother, as a substantially constant, electro-motiveforce.

My invention resides also-in apparatus for producing oscillations of anysuitable frequency by recourse to the apparatus above described.

My invention resides in novel features of structure of the charactershereinafter described.

For an illustration of some of the various forms my apparatus may take,reference is to be had to the accompanying drawing, in which:

Figs. 1 and 2 are graphic representations of thermionic tubecharacteristics.

Fig. 3 is a diagrammatic view illustrating the superposition offluctuating and substantially constant potential upon the plate circuitof a thermionic structure.

Fig. 4C is a diagrammatic view illustrating the impression upon theplate or anode cir force and the effects of coupling of the grid circuitto the plate or anode circuit.

Fig. 6 1s a dlagrammatic vlew of oscillation-producing means wherein afluctuating potential is superimposed upon a substantion is not limitedto the characteristics of this curve, the same being employed merely forillustrative purposes, it being understood that thermionic deviceshaving different characteristic curves regarding grid potential andplate current are comprehended within my invention. The curve indicatesthat as the grid potential rises or becomes more and more positive theplate current increases, assuming a given potential impressed upon theplate circuit.

In Fig. 2 the curve cl is a characteristic of a-thermionic device,ordinates representing the voltages impressed upon the anode or platecircuit and abscissae are resulting plate or anode circuit currents.will be understood that my invention is not limited to thermionicdevices having this particular characteristic, but that any thermionic.devices having different character- 1st1cs are contemplated within mylnvention.

A simultaneous inspection of Figs. 1 and 2 shows broadly that the platecurrent may be made'to increase with rise of potential of the grid andalso by increase in the voltage impressed upon the plate or anodecircuit.

In accordance with my invention I simultaneously change the gridpotential and the Here again it anode circuit voltage; and preferably insuch directions as to cause cumulative change in plate current.

It will be understood respecting the follow-- ing'description that thegrid potential may be varied between any suitable points on a curve suchas 0,- Fig. 1, either within a substantially straight portion thereof/or within a curved portion, or both. And it will be 'further understoodthat as to plate circuit 2, either between points within a substan.

tially straight portion thereof,lor within a curved portion thereof, orboth.

Referring now. to Fig. 3, V is a thermionic device comprising a bulbevacuated to any suitable degree, such as will permit only pure electrondischarge or which will permit discharge due to presence of gas or gasesof any suitable nature and quantity. Within the bulb are disposed theplate or anode p, and electron-emitting body f, as an incandescentfilament, with a control electrode or grid g between them. Thetemperature of the filament fis determined as usual by the amount ofcurrent passed therethrough from a suitable source, as battery I). Inthe plate or anode circuit are connected the winding IT, source B ofsubstantially constant potential, as a battery of suitable voltage, andthe secondary of a. transformer T in whose primary circuit is connectedthe source S of fluctuating or alternating current, this being a genericrepresentation ofany such source,-

including'a dynamo-electric generator, an alternating or direct currentcontrolled or varied by a microphone, received radio telegraphic ortelephonic energy, received telegraphic or telephonic energy from a linewire system, etc. T may be any translating device, as a telephonereceiver in which are to be reproduced s gnals or messages repre--sented by.fiuctuating or alternating current 1 from any source in'theprimary of thetransformer T -Or T may be the primary Winding of atransformer whose secondary delivers energy to any suitable or desirabledevice, as a'telephone receiver or further thermionic devices of thesame character or any other suitable lcharacter.

The grid 9 is connectedto any suitable point in the secondary of thetransformer T1 or to any suitable point with respect to the source B,or, generally, to any suitable point 1 other and producing an effectwhich graphi-' in the external circuit between the filament f and plate9. At s in the grid circuit is shown a battery or condenser. When 8 is abattery it' may serve to give to the grid 9 any suitable normalpotential, for example, a negative potential. The battery or condenser 8maybe, however, omitted, if .desirable.

With the filament f at suitable temperature there will be apredetermined. normal anode or plate circuit current due to the sourceB. Upon the plate circuit potential .or voltage is then impressed agluct'uating or alternating potential by the t1 nsformer T the onepotential being superposedupon the cally may be represented as in Fig. 7The potential of the grid 9 will rise and fall also in suitable orpredetermined relation with respect to the rise andfall of potential1mpressed; upon the anode or plate circuit, a

rise in potential, as indicated by Fig. 1, causing anincrease of platecurrent for a given plate circuit potential, While a simultaneous riseof voltage in the plate circuit due to thetransformer T will cause, asindicated by Fig. 2, a further increase in plate to or dependent uponthe anode or plate circuit potential.

The source S therefore not only varies the potential of the grid and.the potential impressed upon the anode circuit, thereby producing agreater fluctuation in T, but energy offiuctuating or alternatingcurrent may be transferred by the source S into the anode or platecircuit, such energy being.

combined with the energy from source B.

In Fig. 4 the arrangement is similarto that in Fig. 3, except that theplate circuit batteryor source B is-omitted. In this case the energy forthe anode or plate circuit is suppliedbythe source S, the potential fthe gridg, however, being determined by the potential impressed upon theanode or plate circuit. The source of current or condensers maybeemployed or not, as may be found suitable or desirable. The potential ofthe *grid 9 is therefore dependent upon the potential impressed upon theanode circuit, and the grid circuit connection is to .a pointintermediate the filament and plate in the external anode circuit. Thereis in this case no superposition, such as in'Fig.

3, of alternating or fluctuating potential or current upon normallyexisting plate circuit-potential or current.

,In 5' there is in the plate circuit of an oscillator the primary of anoutput trans- ,former T shuntedby a variable condenser C,.in series withthe secondary of the transformer T The grid 9 is connected through asecondary t, in inductive relation with the primary ofthe transformer Tto any suit- :able point on the secondary of the transformer TAccordingly the grid is coupled to the plate circuit, which in turn isconnected to a point whose potential will be intermediate that of thefilament and the plate, the actual potential of the grid g beingdependent upon the potential of such point, the potential produced bythe coupling coil t and the potential of the battery 3, if f employed.Accordingly oscillations will be produced in the plate circuit. whoseenergy is delivered to the secondary of the transformer T for anysuitable-purposes, as for radio telegraphy or telephony,or forimpression upon a line Wire circuit, delivery to amplifying means or forany other purpose, the source S-being generically any source offluctuating or alternating current hereinbetore referred to. I

In Fig. 6 is shown an oscillation-producing arrangement, in general,similar to that shown in Fig. 5, except that in the plate circuit thereis, as in Fin. 3, a source of current or potential B.

In Fig. 8 the grid circuit of an oscillator is coupled by if to theplate circuit, there being); provided, if desired, an adjustable tuningcondenser C in-the grid circuit. parallel to the variable condenser Cand primary of transformer T in the plate circuit, are connected thechoke coil L. battcry l3. and secondary of transformer T In theoscillator of Fig. 5 all or substan- 1 ially all of the energy to beconverted into oscillations is derived from the source S. In Figs. 6 and'8, employing batteries B. the energy of the oscillations may be derivedfrom the battery B and additional energy delivered by the source S; orthe energy for the oscillations may be principally or entirely suppliedby the battery B and the source S with transformer T employed simply forvarying the amplitude of the oscillations. I

In all of the oscillators above described the grid potential varies withvariation of potential of the plate circuit, and inconsequence theamplitude of the oscillations is the greater.

What I claim is:

1. The combination with a thermionic device comprising an anode, cathodeand control electrode, of an anode circuit, a source of fluctuatingcurrent independent of said device impressing fluctuating current uponsaid anode circuit, and an aperiodic connection to said controlelectrode from a point. between the terminals of said source.

2- The combination with a thermionic device comprising an anode, cathodeand con trol electrode, of an anode circuit, a source offluctuating'current in said anode circuit, an aperiodic connection tosaid control electrode from a point between the terminals of saidsource, and'a source of uni-directional potential in said connection.

3. The combination with a thermionic device comprising an anode, cathodeand control electrode, of an anode circuit, a source of fluctuatingcurrent of audio frequency representing sound waves, a transformer whoseprimary includes said source and whose secondary is connected in seriesin said anode circuit, and a connection to said control electrode from apoint between the terminals of said, transformer secondary.

4. The combination with a thermionic device comprising an anode, cathodeand control electrode, of an anode circuit, a source of fluctuatingcurrent, a transformer whose primary includes said source and Whosesecondary is connected in series in said anode circuit, an aperiodicconnection to said control electrode from a point between the terminalsof said transformer secondary, and a source of uni-directional potentialin said connection.

. Thecombination with a thermionic device comprising an anode, cathodeand control electrode, of an anode circuit, a control electrode circuitcoupled thereto for pro vice'comprising an anode, cathode and controlelectrode, of an anode circuit, a control electrode circuit coupledthereto for producing oscillations, a source of fluctuating ourpointbetween the terminals ofsaid source, and a source of uni-directionalpotential in said connection.

7. The combination with a thermionic device comprising an anode, cathodeand control electrode, of an anode circuit, a control electrode circuitcoupled to said anode. circuit for producing oscillations, a source offluctuating current transformed into oscillations by said coupledcircuits, a transformer having said source in its primary circuit andhaving its secondary connected in said anode circuit, and a connectionto said control electrode from a vpoint between the terminals of, saidsecondary.

8. The combination with a thermionic device comprisingan anode, cathodeand control electrode, of an anode circuit, a control. electrode circuitcoupled to said anode cir-,

cuit for producing oscillations, a source of fluctuating current, atransformer having said source in its primary circuit and having itssecondary connected insaid anode circuit, an aperiodic connection tosaidcontrol electrode from a point between the teruni-directionalpotential in said connection.

9. The combination with a thermionic device comprising an anode, cathodeand con trol electrode, of an anode c rcuit normally rent in said anodecircuit, an aperiodic coii- .nection to said control electrode from aininals of said secondary, and a source of lnally without substantialenergy, means delivering fluctuating current to said anode circuit and"constituting substantially the sole source of current for said anodecircuit, a connection to said control electrode from a point between,the terminals of said means, and a source of uni-directional potentialin said connection.

11. The combination with athermionic device comprising an anode, cathodeand control electrode, of anode and control electrode circuits coupledto each other for producing oscillations, a source of fluctuatingcurrent independent of said device and constituting substantially thesole source of current for the production of oscillations, and aconnection to said control electrode from a point between the terminalsof said source.

12. The combination with a thermionic device comprising an anode,cathode and anode circuit, and a connection to said control electrodefrom a point between the terminals of said source.

14. The combination with a thermionic device comprising an anode,cathode and control electrode, of an anode circuit nor mally withoutsubstantial energy, a source of fluctuating current of audio frequencyindependent of said device and representing sound waves and constitutingsubstantiallythe sole source of current for said anode circuit, and aconnection to said control electrode from a point between the terminalsof said source.

15. The combination with a thermionic device comprising an anode,cathode and control electrode, of an anode circuit normally'withoutsubstantial energy, means delivering fluctuating current of audiofrequency representing sound waves to sa d anode circuit andconstituting substantially the sole source of current for said anodecircuit, a connection to said control electrode from a point between theterminals of said means, and a source of uni-directional potential insaid connection.

16. The combination with a thermionic device comprising an anode,cathode and control electrode, of anode and control electrode circuitscoupled to each other for producing oscillations, a source offluctuating current ofaudio frequency independent of said device andrepresenting sound waves and constitutingsnbstantially the sole sourceof current for the production of os -cillations, and a connection tosaid control electrode from a point between the terminals of saidsource.

17. The combination with a thermionic device comprising an anode,cathode and control electrode, of anode and control electrode circuitscoupled to each other for producing oscillations, means deliveringfluctuating current of audio frequency representing sound waves to saidanode circuit and constituting substantially the sole source of currentfor the production of oscillations, a connection to said controlelectrode from a point between the terminals of said means, and a sourceof uni-directional potential in said connection.

18. The combination with a thermionic device comprising an anode,cathode and control electrode, of connections forming anode and controlelectrode circuits, means effecting a feed-back between said anodecircuitand said control electrode, an independent source of fluctuatingcurrent of constant frequency independentof said feedback, said sourceconnected in said anode circuit, and means for subjecting said controlelectrode to a potential varying at the frequency of said sourcecomprising a connection to said control elcetrode from a pointintermediate the terminals of said source.

In testimony whereof I have hereunto affixed my signature this 28th dayof April,

' CORNELIUS D. EHRET.

